Wavefield modelling and 4D-binning for seismic surveys from different acquisition datums

Abstract

A method for maximizing a repeatability between a base seismic survey and a monitor seismic survey of a same surveyed subsurface during a 4-dimensional (4D) project. The method includes receiving first seismic data associated with the base seismic survey; receiving second seismic data associated with the monitor seismic survey, wherein the monitor seismic survey is performed later in time than the base seismic survey; estimating subsurface reflection-points and incidence angles; determining 4D-binning based on the estimated subsurface reflection-points and incidence angles; and maximizing the repeatability between the first seismic data and the second seismic data by using the 4D-binning.

What is claimed is: 
     
       1. A method for generating an image of a subsurface formation, the method comprising:
 receiving first seismic data associated with a base seismic survey of the subsurface formation; 
 acquiring second seismic data during a monitor seismic survey of the subsurface formation, wherein the monitor seismic survey is performed later in time and with different shot-receiver locations than the base seismic survey; 
 estimating subsurface reflection-points and incidence angles for traces in the first seismic data and in the second seismic data; 
 binning the first seismic data and the second seismic data so as to gather the traces of the first seismic data and of the second seismic data, in 4-dimensional (4D) bins determined based on the estimated reflection-points and incidence angles; and 
 processing the 4D bins to generate the image of the subsurface formation. 
 
     
     
       2. The method of  claim 1 , wherein the step of estimating comprises:
 estimating the reflection points for the base and monitor surveys using ray-tracing to target depths; and 
 estimating the incidence angles of rays associated with the reflections points at the target depths. 
 
     
     
       3. The method of  claim 1 , further comprising:
 selecting trace pairs from the first seismic data and the second seismic data using criteria that include similarity of the reflection-point bins and incidence angles. 
 
     
     
       4. The method of  claim 1 , wherein the base seismic survey is a towed-streamer survey and the monitor seismic survey is an ocean-bottom node survey. 
     
     
       5. The method of  claim 1 , wherein there are geometry differences between the first seismic data and the second seismic data. 
     
     
       6. The method of  claim 1 , wherein the step of binning is performed before a step of migrating, which is included in the step of processing the 4D binned data. 
     
     
       7. A computing device for generating an image of a subsurface formation, the computing device comprising:
 an interface configured to receive first seismic data associated with a base seismic survey of the subsurface formation, and to acquire second seismic data during a monitor seismic survey of the subsurface formation, wherein the monitor seismic survey is performed later in time and with different shot-receiver locations than the base seismic survey; and 
 a processor connected to the interface and configured to, 
 estimate subsurface reflection points and incidence angles for traces in the first seismic data and in the second seismic data, 
 bin the first seismic data and the second seismic data so as to gather the traces of the first seismic data and of the second seismic data, in 4-dimensional (4D) bins determined based on the estimated reflection points and incidence angles, and 
 process the 4D bins to generate the image of the subsurface formation. 
 
     
     
       8. The computing device of  claim 7 , wherein the step of estimating comprises:
 estimating the reflection points for the base and monitor surveys using ray-tracing to target depths; and 
 estimating the incidence angles of rays associated with the reflections points at the target depths. 
 
     
     
       9. A method for maximizing a repeatability between a base seismic survey and a monitor seismic survey of a same surveyed subsurface during a 4-dimensional (4D) project, the method comprising:
 receiving first seismic data associated with the base seismic survey; 
 acquiring second seismic data during the monitor seismic survey, wherein the monitor seismic survey is performed later in time and with different shot-receiver locations than the base seismic survey; 
 wavefield separating at least one of the first seismic data and the second seismic data into upgoing and downgoing data; 
 redatuming the upgoing and/or the downgoing data to a target datum; 
 estimating reflection points and incidence angles for traces in the first seismic data and in the second seismic data based on the redatumed upgoing and/or downgoing data; 
 4D-binning the first seismic data and the second seismic data so as to gather the traces of the first seismic data and of the second seismic data, in spatial bins defined based on the reflection points and the incidence angles; and 
 generating an image of the surveyed subsurface by processing the 4D-binned data. 
 
     
     
       10. The method of  claim 9 , wherein the desired target datum is a mirror datum corresponding to a surface that represents a reflection of a surface corresponding to the receivers relative to a surface corresponding to the sources. 
     
     
       11. The method of  claim 9 , wherein the second seismic data is sparse relative to the first seismic data. 
     
     
       12. The method of  claim 9 , wherein the step of 4D-binning comprises:
 estimating reflection points and incidence angles for the base and monitor surveys using ray-tracing to target depths in a redatum geometry. 
 
     
     
       13. The method of  claim 11 , wherein the base seismic survey is associated with towed-streamers and the monitor seismic survey is associated with ocean-bottom nodes. 
     
     
       14. A computing device for maximizing a repeatability between a base seismic survey and a monitor seismic survey of a same surveyed subsurface during a 4-dimensional (4D) project, the computing device comprising:
 an interface for receiving first seismic data associated with the base seismic survey and for acquiring second seismic data associated with the monitor seismic survey, wherein the monitor seismic survey is performed later in time and with different shot-receiver locations than the base seismic survey; and 
 a processor connected to the interface and configured to, 
 wavefield separate at least one of the first seismic data and the second seismic data into upgoing and downgoing data, 
 redatum the upgoing and/or the downgoing data to a target datum, 
 estimate reflection points and incidence angles based on the redatumed upgoing and/or downgoing data, 
 4D-bin the first seismic data and the second seismic data so as to gather traces of the first seismic data and of the second seismic data in bins based on the reflection points and the incidence angles, and 
 generate an image of the surveyed subsurface by processing the 4D-binned data. 
 
     
     
       15. The computing device of  claim 14 , wherein the desired target datum is a mirror datum corresponding to a surface that represents a reflection of a surface corresponding to the receivers relative to a surface corresponding to the sources. 
     
     
       16. The computing device of  claim 14 , wherein the second seismic data is sparse relative to the first seismic data, and the base seismic survey is associated with towed-streamers and the monitor seismic survey is associated with ocean-bottom nodes.